Walter Cannon, Homeostasis and the
Physiological Response to Stress

Slides from:
Introduction to the Autonomic Nervous Sy...
Homeostasis

(A responsibility of the ANS and Endocrine System)


Redrawn after: Kibble JD, Halsey
CR, Homeostasis: In Me...
Components of a negative
feedback control system
Recognizes deviation of
normal set point value

Attempt to restore
set po...
Examples of Physiologic
Controlled Variables
Controlled Variable
(Arterial Blood Sample)

Arterial O2 partial pressure
Art...
Walter Cannon coined the word homeostasis
 Referring to animal systems,
pioneering 20th century
physiologist Walter Canno...
Cannon-Bard theory
Dr. Cannon investigated the
emergency functions of the
sympathetic nervous system and
with Philip Bard ...
Homeostasis (2)

(A responsibility of the ANS and Endocrine System)
Nervous

versus

Endocrine

Wired

Wireless

Neurotran...
Sympathetic Nervous System

The Fright -Flight Or Fight Response

 sympatho-adrenergic system gives rise to fright, fligh...
Sympathetic Nervous System (2)








subject hyperventilates,
gastrointestinal activity reduced,
increased glycoge...
Endocrine Reponses to Stress

 Brain releases corticotrophin-releasing factor (CRF)
to hypothalamic-pituitary portal syst...
Endocrine –Immune System Reponses to Stress

The brain and the immune defense system
 Internal and external stress affect...
Learn more:
Cannon, WB, Organization for Physiological Homeostasis/PDF
Physiological Rev July 1, 1929 9:399-431
Story Time...
Upcoming SlideShare
Loading in …5
×

Walter Cannon, Homeostasis and the Physiological Response to Stress

2,781 views

Published on

http://www.scribd.com/drimhotep_IVMS

0 Comments
1 Like
Statistics
Notes
  • Be the first to comment

No Downloads
Views
Total views
2,781
On SlideShare
0
From Embeds
0
Number of Embeds
53
Actions
Shares
0
Downloads
12
Comments
0
Likes
1
Embeds 0
No embeds

No notes for slide

Walter Cannon, Homeostasis and the Physiological Response to Stress

  1. 1. Walter Cannon, Homeostasis and the Physiological Response to Stress Slides from: Introduction to the Autonomic Nervous System-Lecture Marc Imhotep Cray, M.D. http://www.scribd.com/doc/106694667/IVMS-ANS-PharmacologyIntroduction-Review-of-the-Autonomic-Nervous-System-abridged Marc Imhotep Cray, M.D. Courtesy National Library of Medicine (NLM) 1
  2. 2. Homeostasis (A responsibility of the ANS and Endocrine System)  Redrawn after: Kibble JD, Halsey CR, Homeostasis: In Medical Physiology -The Big Picture; McGraw-Hill ,2009:2 Negative feedback is the major control process used to maintain a stable internal environment See: Wiki-Human-homeostasis/PDF Marc Imhotep Cray, M.D.  The physiologic process of maintaining an internal environment (ECF environment) compatible with normal health Autonomic reflexes maintain set points and modulate organ system functions via negative feedback in pursuit of homeostasis 2
  3. 3. Components of a negative feedback control system Recognizes deviation of normal set point value Attempt to restore set point value Measures control variable COMPARATOR SENSOR stretch receptors, chemo-, baro-, osmo-, and thermoreceptors etc. SET POINT ERROR SIGNAL EFFECTOR CONTROLLED VARIBLE (SEE NEXT SLIDE) Redrawn after: Kibble JD, Halsey CR, Homeostasis: In Medical Physiology -The Big Picture; McGraw-Hill ,2009:2 Important variable maintained within a normal range Marc Imhotep Cray, M.D. + - Negative feedback: Initiation of responses that counter deviations of controlled variables from their normal range NEGATIVE FEEDBACK Effector opposes stimulus 3
  4. 4. Examples of Physiologic Controlled Variables Controlled Variable (Arterial Blood Sample) Arterial O2 partial pressure Arterial CO2 partial pressure Arterial blood pH Glucose Core body temperature Serum Na+ Serum K+ Serum Ca2+ Mean arterial blood pressure Glomerular filtration rate Typical Set Point Value 100 mm Hg 40 mm Hg pH 7.4 90 mg/dL (5 mM) 98.4°F (37°C) 140 mEq/L 4.0 mEq/L 4.5 mEq/L 90 mm Hg 120 mL /min Adopted from: Kibble JD, Halsey CR, Homeostasis: In Medical Physiology The Big Picture; McGraw-Hill ,2009:3 Marc Imhotep Cray, M.D. 4
  5. 5. Walter Cannon coined the word homeostasis  Referring to animal systems, pioneering 20th century physiologist Walter Cannon coined the word homeostasis in 1926  Coordinated physiological reactions which maintain most of the steady states in the body are so complex, and are so peculiar to the living organism, that it was suggested (Cannon, 1929) that a specific designation for these states be employed homeostasis Cannon, WB, Organization for Physiological Homeostasis/PDF Physiological Rev July 1, 1929 9:399-431 Marc Imhotep Cray, M.D. Courtesy National Library of Medicine (NLM) http://en.citizendium.org/wiki/File:William_cannon.jpg #Licensing 5
  6. 6. Cannon-Bard theory Dr. Cannon investigated the emergency functions of the sympathetic nervous system and with Philip Bard developed the Cannon-Bard theory, which proposed that emotional and physiological responses to external situations arise at once and that both prepare the body to deal with the situation. Courtesy National Library of Medicine (NLM) http://www.annals.org/cgi/content/full/134/11/1086 Story Time, Walter Cannon (1871-1945) http://peer.tamu.edu/curriculum_modules/OrganSystems/module_5 /storytime.htm Marc Imhotep Cray, M.D. 6
  7. 7. Homeostasis (2) (A responsibility of the ANS and Endocrine System) Nervous versus Endocrine Wired Wireless Neurotransmitters Hormones Hormones Short Distance Short Distance Long Distance Long Distance Closeness Receptor Specificity Rapid Onset Delayed Onset Short Duration Prolonged Duration Rapid Response Regulation Marc Imhotep Cray, M.D. 7
  8. 8. Sympathetic Nervous System The Fright -Flight Or Fight Response  sympatho-adrenergic system gives rise to fright, flight or fight response in acutely stressful situations  sympathetic dominate over parasympathetic and  subject is aggressive and/ or anxious  cardiac rate, contractile force and conductivity are increase,  blood is re-distributed from viscera to active skeletal muscles by visceral, skin and fat vasoconstriction (+ α-1) and skeletal muscles preferential vasodilatation (+ β-2)  brain releases corticotrophin-releasing factor to hypothalamic-pituitary portal system  The hypothalamic-pituitary axis secretes adrenocorticotropic hormone (ACTH)>>adrenal cortex>>cortisol Marc Imhotep Cray, M.D. 8
  9. 9. Sympathetic Nervous System (2)       subject hyperventilates, gastrointestinal activity reduced, increased glycogenolysis and lipolysis The airways dilate, and adrenal medullary (catecholamines) and cortical secretion (cortisol) increases  This response is seen in humans exposed to psychologicalemotional , as well as physiologic stress  Stress in general is comprised of severe emotional and physical burdens (fear, pain, hypoxia, hypothermia, hypoglycemia, hypotension etc.) Story Time, Walter Cannon (1871-1945) http://peer.tamu.edu/curriculum_modules/OrganSystems/module_5/storytime.htm Marc Imhotep Cray, M.D. 9
  10. 10. Endocrine Reponses to Stress  Brain releases corticotrophin-releasing factor (CRF) to hypothalamic-pituitary portal system  hypothalamic-pituitary axis secretes adrenocorticotropic hormone(ACTH)  This response is seen in humans exposed to psychological-emotional stress, as well as physiologically mediated stress response mechanism, such as ANS stimulation.  Stress in general is comprised of severe emotional and physical burdens (fear, pain, hypoxia, hypothermia, hypoglycemia, hypotension etc.). See: The Wisdom of the Body, by Walter B. Cannon Marc Imhotep Cray, M.D. 10
  11. 11. Endocrine –Immune System Reponses to Stress The brain and the immune defense system  Internal and external stress affects the prefrontal cortex, whereby the limbic system with the hypothalamus is activated  hypothalamic nuclei release CRH to portal blood  blood reaches adenohypophysis, where CRH triggers the release of adenocorticotropic hormone (ACTH), endorphins and met-enkephalin  ACTH works through different pathways in order to protect the body  For example, ACTH stimulates the adrenal cortex to release corticosteroids, which produce immunosuppression. Marc Imhotep Cray, M.D. 11
  12. 12. Learn more: Cannon, WB, Organization for Physiological Homeostasis/PDF Physiological Rev July 1, 1929 9:399-431 Story Time, Walter Cannon (1871-1945) http://peer.tamu.edu/curriculum_modules/OrganSystems/module_5/storytime.htm http://www.scribd.com/doc/106694667/IVMS-ANS-PharmacologyIntroduction-Review-of-the-Autonomic-Nervous-System-abridged Marc Imhotep Cray, M.D. 12

×